We studied the temporal relationships and the patterns of electromyographic activities of the posterior cricoarytenoid and thyreoarytenoid muscles (laryngeal abductor and adductor), the diaphragm and abdominal muscles in anesthetized cats during mechanically induced tracheobronchial and laryngopharyngeal coughs, expiration and aspiration reflexes. The posterior cricoarytenoid muscle activity reached the maxima just before the peak of diaphragmatic activity in both types of cough and aspiration reflexes and slightly before the top of abdominal muscle activity in coughs and the expiration reflex. Thus, this muscle contributes to the inspiratory phase of coughs and aspiration reflex and also to the expulsive phase of coughs and the expiration reflex. The thyreoarytenoid muscle presented strong discharges in the compressive phase of coughs and expiration reflex (during the rising part of the abdominal muscle activity) and in the subsequent laryngoconstriction (following the diaphragmal and/or abdominal muscle activity) in all four reflexes. This muscle was also slightly activated at the beginning of the aspiration reflex. The existence of four phases of the cough reflex is also discussed., I. Poliaček, A. Stránsky, J. Jakuš, H. Baráni, Z. Tomori, E. Halašová., and Obsahuje bibliografii
The cough reflex is an airway defensive process that can be
modulated by afferent inputs from organs located also out of the
respiratory system. A bidirectional relationship between cough
and heart dysfunctions are presented in the article, with the
special insights into an arrhythmia-triggered cough. Albeit rare,
cough induced by cardiac pathologies (mainly arrhythmias)
seems to be an interesting and underestimated phenomenon.
This condition is usually associated with the presence of
abnormal heart rhythms and ceases with successful treatment of
arrhythmia either by pharmacotherapy or by radiofrequency
ablation of arrhythmogenic substrate. The two main hypotheses
on cough-heart relationships – reflex and hemodynamic - are
discussed in the review, including the authors’ perspective based
on the experiences with an arrhythmia-triggered cough.
Individual studies have suggested the utility of fractional exhaled nitric oxide (FeNO) measurement in detecting cough-variant asthma and eosinophilic bronchitis in patients with chronic cough. The aim of this study was to clarify a correlation of cough reflex sensitivity and fractional exhaled nitric oxide in asthmatic children. 25 children with asthma and 15 controls were submitted to cough reflex sensitivity measurement – capsaicin aerosol in doubling concentrations (from 0.61 to 1250 µmol/l) was inhaled by a single breath method. Concentrations of capsaicin causing two (C2) and five coughs (C5) were reported. Fractional exhaled nitric oxide (FeNO) measurement was included. Asthmatic children (11 boys and 14 girls, mean age 9±1 years) and control group (unconfirmed diagnosis of asthma) (6 boys and 9 girls, mean age 8±1 years) were included into the study. FeNO vs. C2 in asthma (Spearman´s rank correlation: -0.146, p=0.49); FENO vs. C5 in asthma (Spearman´s rank correlation: -0.777, p=0.71). We found that there is no correlation between cough reflex sensitivity and fractional exhaled nitric oxide either in children with asthma or in the control group.
New knowledge about the neural aspects of cough has revealed
a complex network of pathways that initiate cough. The effect of
inflammation on cough neural processing occurs at multiple
peripheral and central sites within the nervous system. Evidence
exists that direct or indirect neuroimmune interaction induces
a complex response, which can be altered by mediators released
by the sensory or parasympathetic neurons and vice versa. The
aim of this study was to clarify changes of cough reflex sensitivity
– the activity of airway afferent nerve endings - in asthmatic
children. 25 children with asthma and 15 controls were submitted
to cough reflex sensitivity measurement - capsaicin aerosol in
doubling concentrations (from 0.61 to 1250 µmol/l) was inhaled
by a single breath method. Concentrations of capsaicin causing
two (C2) and five coughs (C5) were reported. Asthmatic children'
(11 boys and 14 girls, mean age 9 ± 1 yrs) cough reflex sensitivity
(geometric mean, with the 95 % CI) for C2 was 4.25 (2.25-8.03)
µmol/l vs. control C2 (6 boys and 9 girls, mean age 8 ± 1 yrs) was
10.61 (5.28-21.32) µmol/l (p=0.024). Asthmatic children' C5 was
100.27 (49.30-203.93) µmol/l vs. control C5 56.53 (19.69-162.35)
µmol/l (p=0.348). There was a statistically significant decrease of
C2 (cough threshold) in the asthmatic patients relative to controls
(p-value for the two-sample t-test of log(C2) for the one-sided
alternative, p-value = 0.024). The 95 % confidence interval for the
difference of the mean C2 in asthma vs. control, [1.004, 6.207].
For C5, the difference was not statistically significant (p-value =
0.348). There was a statistically significant decrease of cough
reflex sensitivity (the activity of airway afferent nerve endings) -
C2 value in the asthmatic children relative to controls.
Since the recognition of angiotensin-converting enzyme inhibitors
(ACEIs)-induced cough, drug has been considered as a potential
cause of chronic cough. This review presents recent knowledge
on drug-induced coughs in patients with chronic cough. The
focus is placed on ACEIs, for which there are a multitude of
studies documenting their associations with cough. Additional
drugs are discussed for which there are reports of cough as
a side effect of treatment, and the potential mechanisms of these
effects are discussed.
The involvement of rapheal and medial parts of the medullary reticular formation in both generation of airway reflexes and changes in breathing were studied in 18 chloralose or pentobarbitone anaesthetized, non-paralyzed cats. Chemical lesions to the medullary midline region (0—4 mm rostral to the obex) produced by localized injections of the neurotoxin kainic acid regularly abolished the cough reflexes evoked from the tracheobronchial and laryngopharyngeal regions and in most cases also the expiration reflex induced from the glottal area. The aspiration reflex elicited from the nasopharynx was spared, but was less intense. However, the signs of cough and expiration reflexes were preserved in the neurogram of the recurrent laryngeal nerve. The experiments have shown the importance of raphe nuclei and other medullary midline structures for the occurrence of cough and expiration reflexes. One possible explanation for the elimination of these expulsive processes is the removal of an important source of facilitatory input to the spinal respiratory motoneurons or to the brainstem circuitries that mediate cough and expiration reflexes . The role of the medullary midline in modulation of eupnoeic breathing and blood pressure is also discussed.
Itch is the most common chief complaint in patients visiting
dermatology clinics and is analogous to cough and also sneeze of
the lower and upper respiratory tract, all three of which are host
actions trying to clear noxious stimuli. The pathomechanisms of
these symptoms are not completely determined. The itch can
originate from a variety of etiologies. Itch originates following the
activation of peripheral sensory nerve endings following damage
or exposure to inflammatory mediators. More than one sensory
nerve subtype is thought to subserve pruriceptive itch which
includes both unmyelinated C-fibers and thinly myelinated Aδ
nerve fibers. There are a lot of mediators capable of stimulating
these afferent nerves leading to itch. Cough and itch pathways are
mediated by small-diameter sensory fibers. These cough and itch
sensory fibers release neuropeptides upon activation, which leads
to inflammation of the nerves. The inflammation is involved in the
development of chronic conditions of itch and cough. The aim of
this review is to point out the role of sensory nerves in the
pathogenesis of cough and itching. The common aspects of itch
and cough could lead to new thoughts and perspectives in both
fields.
We have tested the hypothesis that neurons of both the ventral reticular nucleus and the adjacent parts of the lateral tegmental field (LTF) may be important for the production of motor programs associated with cough, expiration and aspiration reflexes. Our studies were conducted on non-decerebrate, spontaneously breathing cats under pentobarbitone anesthesia. Dysfunction of the medullary LTF region above the obex, produced by uni- or bilateral injections of kainic acid (a neurotoxin), regularly abolished the cough reflex evoked by mechanical stimulation of both the tracheobronchial and laryngeal regions and in most cases also the expiration reflex induced from the glottal area. However, some electrical activity still occurred in the neurogram of the recurrent laryngeal nerve during probing the laryngeal and glottal regions. Interestingly, the aspiration reflex elicited from the nasopharynx regularly persisted, although with lower intensity after the LTF lesion. Nevertheless, successive midcollicular decerebration performed in four cats also abolished the aspiration reflex. These experiments demonstrate the importance of medullary LTF neurons for the normal occurrence of cough and expiration reflexes. One possible explanation for the elimination of these expulsive processes is that the blockade of the LTF neurons may remove an important source of a facilitatory input to the brainstem circuitries that mediate cough and expiration reflexes. In addition, the potential importance of the mesencephalic reticular formation for the occurrence of the aspiration reflex and the role of the LTF in modulating both the eupnoeic breathing and the blood pressure are also discussed., J. Jakuš, A. Stránsky, I. Poliaček, H. Baráni, Ľ. Bošeľová., and Obsahuje bibliografii
We studied the effects of GABA receptor agonists microinjections
in medullary raphé on the mechanically induced tracheobronchial
cough response in anesthetized, unparalyzed, spontaneously
breathing cats. The results suggest that GABA-ergic inhibition
significantly contributes to the regulation of cough reflex by
action of both GABAA and GABAB receptors. The data are
consistent with inhomogeneous occurrence of GABA-ergic
neurons in medullary raphé and their different involvement in the
cough reflex control. Cells within rostral nucleus raphé obscurus
with dominant role of GABAA receptors and neurons of rostral
nucleus raphé pallidus and caudal nucleus raphé magnus with
dominant role of GABAB receptors participate in regulation of
cough expiratory efforts. These cough control elements are
distinct from cough gating mechanism. GABA-ergic inhibition in
the raphé caudal to obex had insignificant effect on cough.
Contradictory findings for GABA, muscimol and baclofen
administration in medullary raphé suggest involvement of
coordinated activity of GABA on multiple receptors affecting
raphé neurons and/or the local neuronal circuits in the raphé
modulating cough motor drive.
Obesity is characterized by chronic, low-grade systemic inflammation. Obesity may also be associated with chronic cough. The aim of this pilot study was to clarify relation of cough reflex sensitivity and body mass index (BMI) in children with chronic cough. Altogether 41 children having symptoms of chronic cough were submitted to cough reflex sensitivity measurement. We assessed the relation of cough reflex sensitivity (CKR) due to BMI. Cough reflex sensitivity was defined as the lowest capsaicin concentration which evoked two (C2) or five (C5) coughs. Capsaicin aerosol in doubling concentrations (from 0.61 to 1250 µmol/l) was inhaled by a single breath method (KoKo DigiDoser; nSpire heath Inc, Louisville, CO, USA), modified by the addition of an inspiratory flow regulator valve (RIFR; nSpire heath Inc, Louisville, CO, USA). BMI was calculated. Pulmonary function was within normal range. Concentrations of capsaicin causing two (C2) and five coughs (C5) were reported. Children' (22 boys and 19 girls, mean age 6.8 years) cough reflex sensitivity (median, with the InterQuartile Range) for C2 was 19.5 (73.4) µmol/l; for C5 it was 78.1 (605.5) µmol/l. We have noticed statistically significant relation of the cough reflex sensitivity (C5) and body mass index (P<0.0001); however, the effect size was small, R2 =0.03. Increase of body mass index in one unit is associated with -34.959 µmol/l decrease of C5. We did not find a statistically significant relation between C2 and BMI (P=0.41). The median value of CKR (C2) in boys is not statistically significantly different than the median value of CKR (C2) in girls (P-value 0.5). The median value of CKR (C5) in boys is not statistically significantly different than the median value of CKR (C5) in girls (P-value 0.5). Increase of body mass index in children suffering from chronic cough relates to decrease of cough reflex sensitivity (C5 value).